The present invention relates to aerosol dispensing devices, and in particular to valve assemblies that provide the automatic release of aerosol content in a single burst without requiring the use of electrical power.
Aerosol cans dispense a variety of ingredients. Typically, an active is mixed with a propellant which inside the can is at least partially in a gas state, but may also be at least partially dissolved into a liquid containing active. Typical propellants are a propane/butane mix or carbon dioxide. The mixture is stored under pressure in the aerosol can.
The active mixture is then sprayed by pushing down/sideways on an activator button at the top of the can that controls a release valve. For purposes of this application, the term “active chemical” is used to mean that portion of the content of the container (regardless of whether in emulsion state, single phase, or multiple phase), which is in liquid phase in the container (regardless of phase outside the container) and has a desired active such as an insect control agent (repellent or insecticide or growth regulator), fragrance, sanitizer, and/or deodorizer alone and/or mixed in a solvent, and/or mixed with a portion of the propellant.
Pressure on a valve control button is typically supplied by finger pressure. However, for fragrances, deodorizers, insecticides, and certain other actives which are sprayed directly into the air, it is sometimes desirable to empty the entire contents of the aerosol container at once. While this can be done manually, applying constant finger pressure until the container is empty is tiring and impractical. Furthermore, when delivering an insect repellant or fumigant to an area, it would typically be desirable for the user to be located elsewhere while the active chemical is being delivered.
Prior art systems exist for automatically distributing the entire active content of an aerosol container in one burst. The user depresses the trigger on the aerosol content to lock the trigger in the dispense position. See e.g. U.S. Pat. No. 5,791,524. However, aerosol content begins flowing the moment that the trigger is depressed, thereby having a period of time in which the person activating the dispensing is proximate the dispensed chemical. Such systems have limitations, particularly where the chemical being dispensed is an insecticidal fumigant.
Thus, a need still exists for improved, inexpensive automated aerosol dispensers that do not require electrical power, provide a single burst of the active chemical that essentially exhausts the contents of the supply, and do so with a time delay after initial activation.